1. Field of the Invention
The present invention relates to a substrate cleaning apparatus cleaning a semiconductor substrate, a glass substrate for a liquid crystal display, a glass substrate for a photomask or a substrate for an optical disk (hereinafter simply referred to as xe2x80x9csubstratexe2x80x9d) by spraying hot water mist thereto.
2. Description of the Background Art
A product such as a semiconductor or a liquid crystal display is manufactured by performing a series of processing such as cleaning, resist coating, exposure, development, etching, formation of an interlayer dielectric film, heat treatment and the like on a substrate. Among these, cleaning is processing of removing contaminants such as particles adhering to the substrate, which is increasingly regarded as important following recent progress of refinement and complication of patterns.
A representative substrate processing apparatus employed in general is the so-called spin scrubber rotating a substrate while bringing a brush into contact with the surface of the substrate or approaching the former to the latter thereby scrubbing out contaminants such as particles adhering to the surface of the substrate. In this technique of forcibly scrubbing out the contaminants through frictional force of the brush, however, the brush disadvantageously damages the surface of the substrate although a strong cleaning effect is attained.
Therefore, a non-contact substrate cleaning apparatus employing no brush has recently been watched with interest. For example, a system of supplying ultrasonic waves to a liquid coming into contact with the surface of a substrate or a system of spraying pure water mist at a high speed is being studied. The system spraying pure water mist collides small droplets substantially identical in size to the contaminants adhering to the surface of the substrate with the contaminants from random directions, to attain a high cleaning effect. Particularly when spraying hot water mist containing droplets having a temperature higher than the room temperature at a high speed, an activation effect can also be attained due to thermal energy of the droplets, and hence it is expected that a higher cleaning effect will be attained.
In general, however, it is difficult to form hot water mist containing small droplets having both high kinetic energy and high thermal energy. When high-temperature steam is merely injected toward a substrate, for example, the steam is not readily condensed and no hot water mist is formed.
The present invention is directed to a substrate cleaning apparatus cleaning a substrate by spraying thereon hot water mist.
A substrate cleaning apparatus according to the present invention, cleaning a substrate by spraying thereon hot water mist, comprises a steam guiding and feeding part for guiding and feeding steam obtained by heating pure water and a tubular discharge nozzle fixedly provided on the steam guiding and feeding part for forming hot water mist by guiding a gas mixture prepared by mixing steam and carrier gas with each other while condensing the steam and spraying the hot water mist onto the substrate.
The carrier gas functions as a medium absorbing latent heat of condensation for smoothly progressing condensation of water vapor and efficiently forming hot water mist. The formed hot water mist is accelerated due to dilation of the carrier gas increased in temperature by absorbing latent heat of condensation, and sprayed onto the substrate W as high-speed hot water mist attaining a high cleaning effect.
According to a preferred embodiment of the present invention, the substrate cleaning apparatus further comprises a gas discharge pipe discharging the carrier gas in the steam guiding/feeding part, and a gas discharge direction of the gas discharge pipe aligns with a fluid passage direction of the discharge nozzle.
The gas mixture of the steam and the carrier gas discharged from the gas discharge pipe efficiently flows into the discharge nozzle, so that high-temperature hot water mist can be readily formed.
According to another embodiment of the present invention, a substrate cleaning apparatus cleaning a substrate by spraying hot water mist thereto comprises a pure water supply part supplying pure water for forming dry steam, a steam generation part communicating with the pure water supply part for heating the pure water supplied from the pure water supply part and generating steam, a steam heating part communicatively connected with the steam generation part for heating the steam generated in the steam generation part and forming dry steam, and a discharge nozzle fixedly provided on the steam heating part for forming hot water mist by guiding the formed dry steam while condensing the dry steam and spraying the hot water mist to the substrate.
The steam heating part can completely vaporize part of the pure water not completely vaporizable in the steam generation part so that dry steam of high purity can be formed through a simple miniature structure. Consequently, hot water mist containing a small quantity of impurities and attaining a high cleaning effect can be sprayed to the substrate.
Accordingly, an object of the present invention is to provide a substrate cleaning apparatus capable of spraying hot water mist attaining a high cleaning effect to a substrate.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.